Yes, I think he was funny back in the 80's when he was on NBC and for awhile he was funny after moving to CBS. At first, I merely thought him mean-spirited, as many of his "jokes" were actually ambushes of people on the street who were not in on the joke. Eventually, he just got sort of zany and reminded me of the Tonight Show when Steve Allen hosted it.
Now, he is just a bitter old man. He seldom smiles, and merely scowls a bitter scowl. His jokes are lame and you can see them coming a mile away. I remember one from a few years ago. It was right after Pres. Bush had been to China, and he tried to open some doors that would not open. Letterman's joke: he announced that the President of the United states would be on. I said to my wife: "watch as he cuts to a shot of some locked doors jiggling as if some fool on the other side is trying to get in", and that, of course, was the "joke".
Another Dave masterpiece was when Obama went to Mexico. Dave lauded Obama as a great president "the first to actually visit our neighbor to the south in a long time". He then said that our previous president thought he had been to Mexico-and he cuts to a photo of a Taco Bell with a pic of Bush badly superimposed over it. So, several months into the Obama presidency, and he has yet to make fun of the Fűhrer and continues with the "boy that Bush was a big dummy" type of joke.
I do not think CBS even considers him a comedian any more. I think his job is to be a bitter old fart who spews leftist bile and who gets away with it under the guise of satire. These remarks about both Palins are truly disgusting. I'd write to complain to CBS but they would probably take my letter as proof that Letterman is doing his job.
Letterman was so NOT funny they passed him up in ‘92 for the Late Show and recently again with Conan. He has always been nothing but a sarcastic idiot who only makes fun of other people.